Well it is frowned upon, because it's viewed as milking the reward pool twice, and people don't like the idea of people recycling their stuff....it is kind of sleazy if you think about it. However, if you're transparent, and say, you got like ten cents for a post, but you feel like it's your best work, i see no issue with very rarely reposting something, as long as you explain it. 
For me, I am giving all SBD rewards to @ackza, because I trust him, and I think he is definitely changing the world, with his visions of helping to get a ton of Africans on board with Steem, buying them smartphones, and getting them pre-paid cards for internet. People like him are kind of rare, so I believe any extra, accidental upvotes can go towards him.
I value my reputation more than anything, so I want to be transparent about this situation of me wanting my best content on Dtube, but want people to know that I see no option to decline rewards. My solution is coming from my desire to help @ackza realize his huge dreams of improving the people's lives.